Idle emacs taking 100% cpu - how to track it?

Idle emacs taking 100% cpu - how to track it?

[Marcin Kasperski]

For some time I observe some irritating problem: when I leave some
emacs running (say, on another virtual desktop) and unused, after some
time it starts taking 100% CPU (on the fast modern machine). Sometimes
it is still responsive and I can start using it again (while it
handles keystrokes it usually stop eating CPU but when I leave it it
starts hogging again), sometimes it seems frozen (does not repaint
buffer windows).

I use debian's snapshot version (at the moment GNU Emacs 22.0.95.1
(i486-pc-linux-gnu, GTK+ Version 2.8.20))

First I suspected server mode, but replacing it with gnuserv did not
change anything.

Now I suspect 'something' updating semantic.cache (it happened to me
that when I had returned to hogging emacs, found it frozen and
pressed Ctrl-G, after some time semantic.cache has been displayed).
But I am not sure.

Has anybody faced similar behaviour?

What can I do to track the problem (I of course suspect some elisp
code going wild, but how to check what exactly is wrong...)?

Re: Idle emacs taking 100% cpu - how to track it?

[Stefan Monnier]

> For some time I observe some irritating problem: when I leave some
> emacs running (say, on another virtual desktop) and unused, after some
> time it starts taking 100% CPU (on the fast modern machine). Sometimes
> it is still responsive and I can start using it again (while it
> handles keystrokes it usually stop eating CPU but when I leave it it
> starts hogging again), sometimes it seems frozen (does not repaint
> buffer windows).

You're running cedet-NN.MMpre3, upgrade to pre4.


        Stefan

Re: Idle emacs taking 100% cpu - how to track it?

[Marcin Kasperski]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>> For some time I observe some irritating problem: when I leave some
>> emacs running (say, on another virtual desktop) and unused, after some
>> time it starts taking 100% CPU (on the fast modern machine). Sometimes
>> it is still responsive and I can start using it again (while it
>> handles keystrokes it usually stop eating CPU but when I leave it it
>> starts hogging again), sometimes it seems frozen (does not repaint
>> buffer windows).
>
> You're running cedet-NN.MMpre3, upgrade to pre4.

Thank you for the hint, I just did it. Does it mean I faced known old bug?

Re: Idle emacs taking 100% cpu - how to track it?

[Lennart Borgman (gmail)]

Marcin Kasperski wrote:
> Stefan Monnier <monnier@iro.umontreal.ca> writes:
> 
>>> For some time I observe some irritating problem: when I leave some
>>> emacs running (say, on another virtual desktop) and unused, after some
>>> time it starts taking 100% CPU (on the fast modern machine). Sometimes
>>> it is still responsive and I can start using it again (while it
>>> handles keystrokes it usually stop eating CPU but when I leave it it
>>> starts hogging again), sometimes it seems frozen (does not repaint
>>> buffer windows).
>> You're running cedet-NN.MMpre3, upgrade to pre4.
> 
> Thank you for the hint, I just did it. Does it mean I faced known old bug?


Yes, you need the version of cedet above when you are using Emacs 22.